Suspension structure of liner plates

ABSTRACT

A structure for supporting liner plates of cast hard alloy, in which the configuration of the plates maintains a substantially constant cross-section to eliminate porosity by assuring uniform cooling.

United States Patent 1 DeGroot et al. July 10, 1973 SUSPENSION STRUCTURE OF LINER [56] References Cited PLATES UNITED STATES PATENTS [75] Inventors: John E. DeGroot, Pompano Beach, 2,341,559 2/l944 Keefer 51/9 F 121., Bernard Fuerst, Grand Rapids, 2,909,870 10/ I959 Barnes 5 I19 Mich. [73 l Assignee: Benfur Manufacturing Company, Primary ExaminerCharles J. Myhre Grand Rapids, Mich. Assistant Examiner-F. D. Shoemaker Attorney-Glenn B. Morse [22] Filed: Dec. 22, 1971 21 Appl. No.: 210,653 ABSTRACT A structure for supporting liner plates of cast hard al- [52] U S Cl 51/268 51/9 loy, in which the configuration of the plates maintains [51] B24, 35/04 a substantially constant cross-section to eliminate po- [58] Field of S earcii 74/609; 51 9, 8, by assuring 51/268 5 Claims, 5 Drawing Figures SUSPENSION STRUCTURE OF LINER PLATES SUMMARY OF THE INVENTION It is common practice to line the interior of abrasive blasting machines with plates of extremely hard cast alloy to resist the effects of the high-velocity abrasive particles. A very widely-used form of this type of machine involves a rotor shaped like a paddle wheel, and provided with a central open area into which abrasive particles are fed at a controlled rate. The rotation of the wheel accelerates these particles into a highvelocity stream which is impinged upon workpieces of various description, either to remove casting scale, or process the surface of the workpieces for a variety of purposes. Anything in the path of these abrasive particles must necessarily be a replaceable component, and these expandable items are marketed in substantial quantities. The frequency with which they must be replaced requires that the suspension of these plates within the machine be of such a nature as to require a minimum of effort in removal and replacement. The very hardness of the alloy material of which the plates are cast practically prohibits machining operations, and the inital configuration of the cast material must somehow provide for interengagement with support structure associated with an outer housing.

The usual structure for supporting these plates has used integrally-formed lugs cast on the back surface of the plates. These necessarily produce abrupt changes in thecross-section of the plates resulting in points of increase in thickness. These sudden changes in crosssection cause non-uniform cooling of the cast material, which results in the migration of gaseous inclusions toward the area which is last to solidify. The resulting porosity in these areas makes the plates less capable of resisting the extreme abrasion for which they are designed, which often produces a wear-through at these points of thickness increase before the remainder of the plate has been substantially worn.

The present invention is directed primarily at the provision of a configuration on the back of the plate which will engage adequate support structure without seriously altering the cross-section of the plate to a point sufficient to induce an abrupt cooling gradient. Preferably, the discontinuity formed in the back of the plate is just sufficient to engage a formed sheet-metal clip with sufficient security so that the clip forms a hook that normally interconnects with some convenient form of projection on the inside of the outer housing. In this manner, the principal extension necessary to form an interlock between the plate and the housing is provided by the separable sheet-metal hook, thereby eliminating the change in cross-section of the casting that would be necessary to provide this same degree of extension.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-section of a conventional rotary blasting machine housing, provided with the structure incorporating the present invention for supporting the liner plates.

FIG. 2 is a viewon an enlarged scale over that of FIG. 1, showing the back of one of the liner plates in plan view, with the supporting clip installed in position.

FIG. 3 is a section on the plane 3-3 of FIG. 2.

FIG. 4 is a perspective view of the supporting clip.

FIG. 5 is a cross-section similar to that of FIG. 3, but showing a modified form of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The blasting machine shown in FIG. 1 includes a con ventional rotor structure mounted on the shaft 10 for rotation in suitable bearings (not shown). The so-called cage 11 is normally provided to control the admission of abrasive particles into the central area of the rotor for release into the area adjacent the paddletype blades of the rotor, which do not appear in the drawing. This portion of the machine is conventional and forms no part of the present invention. The chamber surrounding the rotor is defined by a series of peripheral liner plates 12-46. The plates 12, 13, 15 and 16 are secured to the outer housing structure 17, and the plate 14 is associated with the removable cover 18. The position of the cage 11 will normally be selected so that the stream of blast particles will be directed downward, as viewed in FIG. 1. Nevertheless, enough stray particles will be moving around in a random fashion within the rotor chamber to necessitate the presence of the hard replaceable liner plates, in order to eliminate the wear on the structural sections of the housing 17. The removal and replacement of the liner plates is most easily affected through the opening available through removal of the cover 18 and the top plate 14, which makes it preferable that the plates be capable of disengagement from the housing by a simple upward movement in a general direction parallel to the housing wall with which they are associated. It is conventional to provide liner plates at the axially-opposite ends of the housing, in addition to those surrounding the periphery. These sector-shaped plates are identified at 19-23. If desired, these may be suspended from the housing in the same manner as will be discussed in the following text in connection with the peripheral liner plates.

In the preferred form of the invention, the back surface of a plate is provided with a pair of spaced offsets shown at 24 and 25 in FIG. 2. These are substantially parallel throughout the length of the plate, except for a short portion indicated at 24a and 25a in which the spacing deviates from parallelism to provide a wedgeconfiguration for receiving the edges 26 and 27 of the suspension clip 28. These edges are preferably similarly displaced from parallelism to register with the sections 240 and 25a of the offsets in the back of the plate. The portions 24a and 25a are also inclined with respect to the plane of the back of the plate to form oppositelyfacing dovetail surfaces to maintain the suspension clip 28 solidly in connection with the plate after it is driven into wedging engagement. The remainder of the offsets 24 and 25 along the length of the blade may either be rectangular, or may be a continuation of the dovetail configuration. The suspension clips 28 are slipped in from'the bottom, as viewed in FIG. 2, and tapped into the finally-assembled position. If desired, the wedging action provided by the sections 240 and 25a may be either replaced or supplemented by the presence of small abutments at the points indicated at 29 and 30.

The suspension clip is best shown in FIG. 4. This clip provides a tab 31 connected to the central base portion 32 by the transverse portion 33. The tab 28 is preferably formed of bent sheet metal, and this configuration provides a considerable degree of spring-type resilience such that the tab 33 can be designed to deflect slightly on interengagement with a lug 34 on the inside of the housing. The clip should be oriented with respect to the plates such that a downward thrust is necessary in order to engage the tabs 31 with the housing lug, with this same direction of force tending to increase the wedging action in the portions 240 and 25a on the plates. If desired, this hook-over arrangement may be replaced by a standard fastening (such as a bolt or nut) engaging the tab 31.

The modification shown in FIG. is similar in principle to that previously described, except in the use of outwardly-facing dovetail surfaces, rather than the inwardly-facing surfaces discussed in connection with the previous modification. The plate 35 may be provided with recesses 36 terminating in the dovetail surfaces 37 receiving the flanges 38 of the clip 39. The recesses 36 may be continuous along the length of the plate, except for a small portion similar to the portions 24a and 25a of FIG. 2, which exhibit a displacement from parallelism to provide the wedging action. The flanges 38 are preferably disposed to register with this same wedge configuration. The remainder of the supporting clip 39 is similar to that shown in FIG. 4. The offset portions of the liner plate shown at 40, and the similar offsets in the peripheral plates illustrated-in FIG. 1, are conventional, and form no part of the present invention. These overlapped areas are provided to minimize the passage of abrasive particles out into the space between the liner plates and the housing 17.

It may be noted in passing that the tapered configuration characteristic of the surfaces 24a and 25a, and the abutments 29 and 30, may conceivably be replaced by a sufficiently heavy forced fit to generate the necessary friction to maintain the placement of the supporting clips with respect to the liner plates. This of necessity requires a sufficient control of tolerances in casting procedures to produce something of a problem. It is for this reason that the wedging action, or the abutments,

' are preferable.

The particular embodiments of the present invention which have been illustrated and discussed herein are for illustrative purposes only and are not to be considered as a limitation upon the scope of the appended claims. In these claims, it is our intent to claim the entire invention disclosed herein, except as we are limited by the prior art.

We claim:

1. A liner structure for a machine housing, said structure including a plurality of plates of cast material secured to the inside of said housing, wherein the improvement comprises:

abutment means providing a set of dovetail surfaces on the back of at least certain of said plates, said surfaces defining portions of ridges extending along said back providing a substantially continuous cross-section along said plate with respect to the thickness thereof, and

a clip having opposite portions engageable with said dovetail surfaces, and a portion normally engaged to said housing.

2. A structure as defined in claim 1, wherein said dovetail surfaces face inwardly toward the center of said plate, and said clip has the outer edges of the base thereof normally engaging said surfaces, said clip having a tab spaced from the said base and normally engaging a projection on the inside of said housing.

3. A structure as defined in claim 2, wherein said clip is of bendable sheet material, and said tab is connected to said base by a portion extending from said base and disposed transversely to said dovetail surfaces.

4. A structure as defined in claim 1, wherein said dovetail surfaces are disposed at a tapered spaced relationship.

5. A structure as defined in claim 1, wherein at least one of said dovetail surfaces is interrupted by an abutment to limit the freedom of movement of said clip along said surfaces. 1 

1. A liner structure for a machine housing, said structure including a plurality of plates of cast material secured to the inside of said housing, wherein the improvement comprises: abutment means providing a set of dovetail surfaces on the back of at least certain of said plates, said surfaces defining portions of ridges extending along said back providing a substantially continuous cross-section along said plate with respect to the thickness thereof, and a clip having opposite portions engageable with said dovetail surfaces, and a portion normally engaged to said housing.
 2. A structure as defined in claim 1, wherein said dovetail surfaces face inwardly toward the center of said plate, and said clip has the outer edges of the base thereof normally engaging said surfaces, said clip having a tab spaced from the said base and normally engaging a projection on the inside of said housing.
 3. A structure as defined in claim 2, wherein said clip is of bendable sheet material, and said tab is connected to said base by a portion extending from said base and disposed transversely to said dovetail surfaces.
 4. A structure as defined in claim 1, wherein said dovetail surfaces are disposed at a tapered spaced relationship.
 5. A structure as defined in claim 1, wherein at least one of said dovetail surfaces is interrupted by an abutment to limit the freedom of movement of said clip along said surfaces. 